1. Field of the Invention
This invention relates to an optical recording method and optical recording medium. In particular, it relates to a method of recording and reproducing an optical recording disk such as a CD-R or DVD-R, and to an optical recording medium formed by data pits using this recording method.
2. Description of the Related Art
In recent years, with the spread of optical recording media such as CD (compact disks) exclusively for read-out, CDs which can be recorded (CD-R, CD-RW) are now also becoming widespread.
Unlike the CD of the prior art, users can record information on a CD-R or on a CD-RW, and the signal after recording can be reproduced by commercial CD players as it complies with the standard CD specification.
A method of obtaining an optical recording medium for CD-R is for example proposed in Japanese Patent Application Laid-Open 2-42652, wherein a recording layer is provided by spin coating a dye on a substrate and then providing a metal reflecting layer on the back.
The speed of recording drives has increased from the flat speed (approximately 1.3 m/s), and higher performance 4–12 speed (approximately 15.6 m/s) recording models are now becoming widespread.
However, if prior art CD-R media are used for recording at high speeds such as 12 speed, the signal quality deteriorated compared to flat speed recording. Specifically, when recording at high speeds, there is a narrow margin relative to the recording power, and recording errors occurred depending on the combination of recorder and player.
Hence, in Japanese Patent Application Publication No. 2858067, a method is proposed where an EFM signal is recorded on a CD-R at a pulse width of (n+P) 231.4 ns×Vr/Vw, where n=3, 4, 5, 6, 7, 8, 9, 10, 11 and −0.5<P<−0.2, and the pulse width is made shorter the faster the recording speed. Also, in Japanese Patent Application Laid-Open 10-64065, it is proposed to reduce the value of the bottom power of the recording pulse the faster the recording speed.
It is therefore an object of this invention to resolve the problems in the prior art in view of the above situation, and achieve the following purposes.
Specifically, it is an object of this invention to provide a recording method for an optical recording medium which is very well suited to high-speed recording, and to a playable optical recording medium comprising data pits formed by this recording method.